The Epidermal Growth Factor Receptor (EGFR) gene is frequently amplified in a variety of cancer tumors. In some cancers, the resulting over-expression of EGFR mRNA and/or protein activates downstream signal transduction pathways, which contributes to cell cycle dysregulation and tumorigenesis. In addition to over-expressing wild-type EGFR (wtEGFR), some tumor cells also express a rearranged form of EGFR in which exons 2 through 7 are deleted, thereby juxtaposing exons 1 and 8. This mutant EGFR is known as EGFRde2-7 or EGFR mutant variant III (EGFRvIII). The EGFRvIII protein product induces ligand-independent cell signaling, which further increases the tumorigenic potential of cells expressing the mutation.
Anti-EGFR therapies are designed to target and destroy cancer cells that overexpress EGFR and/or express EGFRvIII. Thus, assessment of EGFR and/or EGFRvIII RNA expression profiles may serve as important diagnostic tools in the field of oncology.